In the manufacture of cameras for industrial applications, such as vision systems, the use of relatively small lenses including the ubiquitous M12 base design is extremely common. Typically, the camera body includes a recessed mounting hole with internal threads to receive the external threads of the lens. During manufacture and/or in the field, it is desirable to install, and sometimes remove, the lens unit from the camera body. In doing so, the user engages the exposed face of the lens, generally in the region of the rim surrounding the optic, and turns to either tighten or loosen it.
It is common for the front and side surfaces of the lens to be relatively free of detents or other structures that can allow insertion of a tool to assist in turning the lens. When there is sufficient clearance, the user simply grasps the sides of the lens body with sufficient gripping force and tightens or loosens the lens to a desired degree. However as cameras become increasingly compact, particularly those used in vision system applications the like the In-Sight system available from Cognex Corporation of Natick, Mass., the lens becomes lower-profile and closely mounted. In such cases there may be insufficient clearance to grasp the lens body effectively. The problem is illustrated in the schematic cutaway view of the front face 100 of a vision system camera. In this example, the lens 110 is surrounded by a rig illumination structure 120 (and other bezels that) that leaves a relatively small gap G. In this arrangement, it is challenging to tighten or loosen the lens without a special tool, and even with a tool, there are typically no formations for the tool to engage on many lens types.
Accordingly, it is desirable to provide a mechanism for tightening and loosening a lens where there exists low clearance between the sides of the lens and the surrounding camera structures. This mechanism should be straightforward to use by both manufacturers and subsequent end users and allow for sufficient torque to be applied to the lens to ensure its secure tightening to and/or loosening from a mounting hole as desired. The mechanism should also avoid scratching or damaging the lens optic or surrounding face and sidewalls.